A is a rapid, automatic, and involuntary response to a specific stimulus. These actions are fundamental to survival because they allow the body to react nearly instantaneously to protect itself—such as pulling your hand away from a hot stove—before the brain even processes the sensation of pain. The Reflex Arc
: The muscle or gland that carries out the response (e.g., a muscle contracting to move a limb). Key Types of Reflexes
: Carries the response signal away from the central nervous system to the target organ.
: Detects the stimulus (e.g., heat, pressure, or a pinprick).